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/*++ BUILD Version: 0001
Copyright (c) 1990 Microsoft Corporation
Module Name:
VINT.H
Abstract:
This module contains macro support for manipulating virtual
interrupt bit from v86 mode and 16bit protect mode. FCLI/FST/FIRET
result in exact behavior of these instructions on the chip without
trapping.
Author:
Sudeepb 08-Dec-1992 Created
Revision History:
sudeepb 16-Mar-1993 added FIRET
--*/
/*
See \nt\private\inc\vdm.h for a complete list
of the NTVDM state flag bit definitions
INTERRUPT_PENDING_BIT - set if interrupts pending
VIRTUAL_INTERRUPT_BIT - This bit always correctly reflects the interrupt
disbale/enable state of the vDM while in 16bit land.
MIPS_BIT_MASK - tells whether VDM is running on x86/mips
EXEC_BIT_MASK - tells if DOS is in int21/exec operation.
*/
#define INTERRUPT_PENDING_BIT 0x0003
#define VIRTUAL_INTERRUPT_BIT 0x0200
#define MIPS_BIT_MASK 0x400
#define EXEC_BIT_MASK 0x800
#define RM_BIT_MASK 0x1000
#define RI_BIT_MASK 0x2000
#define FIXED_NTVDMSTATE_SEGMENT 0x70
#define FIXED_NTVDMSTATE_OFFSET 0x14
#define FIXED_NTVDMSTATE_LINEAR ((FIXED_NTVDMSTATE_SEGMENT << 4) + FIXED_NTVDMSTATE_OFFSET)
#define FIXED_NTVDMSTATE_REL40 0x314
#define FIXED_NTVDMSTATE_SIZE 4
#define NTIO_LOAD_SEGMENT 0x70
#define NTIO_LOAD_OFFSET 0
#define pNtVDMState ((PULONG)FIXED_NTVDMSTATE_LINEAR)
#define VDM_TIMECHANGE 0x00400000
/* ASM
; FCLI macro should be used in v86mode/16bit preotect mode code to replace
; costly cli's. Please note that this macro could destroy the Overflow
; bit in the flag.
FCLI macro
local a,b,c
push ds
push ax
mov ax,40h
mov ds,ax
lahf
test word ptr ds:FIXED_NTVDMSTATE_REL40, MIPS_BIT_MASK OR RI_BIT_MASK
jnz short b
lock and word ptr ds:FIXED_NTVDMSTATE_REL40,NOT VIRTUAL_INTERRUPT_BIT
a:
sahf
pop ax
pop ds
jmp short c
b:
cli
jmp short a
c:
endm
;
; FSTI macro should be used in v86mode or 16bit protectmode code to replace
; costly sti's. Please note that this macro could destroy the Overflow bit
; in the flag.
FSTI macro
local a,b,c
push ds
push ax
mov ax,40h
mov ds,ax
lahf
test word ptr ds:FIXED_NTVDMSTATE_REL40, INTERRUPT_PENDING_BIT
jnz short b
test word ptr ds:FIXED_NTVDMSTATE_REL40, MIPS_BIT_MASK OR RI_BIT_MASK
jnz short b
lock or word ptr ds:FIXED_NTVDMSTATE_REL40, VIRTUAL_INTERRUPT_BIT
a:
sahf
pop ax
pop ds
jmp short c
b:
sti
jmp short a
c:
endm
FIRET MACRO
local a,b,d,e,f,g,i,j,k
push ds
push ax
;; Do real IRET on MIPS or if interrupts are pending
mov ax,40h
mov ds,ax
test word ptr ds:FIXED_NTVDMSTATE_REL40, MIPS_BIT_MASK OR RI_BIT_MASK
jnz short b
;; running on x86 can assume 386 or above instructions
push bp
mov bp,sp
mov ax,[bp+10] ; get flags
pop bp
test ax,100h ; test if trap flag is set
jnz short b ; if so, do iret
test ax,200h ; test if interrupt flag is set
jz short i ; ZR -> flag image has IF not set
lock or word ptr ds:FIXED_NTVDMSTATE_REL40, VIRTUAL_INTERRUPT_BIT
test word ptr ds:FIXED_NTVDMSTATE_REL40, INTERRUPT_PENDING_BIT
jnz short b
j:
xchg ah,al ; AH=low byte AL=high byte
cld
test al,4 ; check direction flag
jnz short d ;
e:
test al,8 ; check overflow flag
jnz short f ; go to f if flag image has OF set
jo short k ; go to k to reset OF
g:
sahf ; set low byte of flags from ah
pop ax
pop ds
retf 2 ; IRET and discard flags
i:
lock and word ptr ds:FIXED_NTVDMSTATE_REL40,NOT VIRTUAL_INTERRUPT_BIT
jmp short j
f:
jo short g ; all OK if OF bit set in real flag
; set the overflow bit in real flag
push ax
mov al,127
add al,2 ; will set OF
pop ax
jmp short g
k:
; reset the OF
push ax
xor al,al ; will reset OF
pop ax
jmp short g
d:
std
jmp short e
b:
pop ax
pop ds
iret
endm
*/
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